126 TRANSACTIONS OP THE [MAY 23, 



Prof. Ogden N. Rood, of Colunibia College, delivered the last 

 lecture of the Public Course on " Color," illustrated. At the close 

 of the discourse a vote of thanks was extended to Prof. Rood, and 

 the meeting adjourned. 



May 23d, 1892. 

 Stated Meeting. 



The President, Dr. Hubbard, in the chair. Seventeen persons 

 present. 



The minutes of May 16th were read and approved. 

 The following papers were then read : — 



Sucrose, Dextrose, and Levulose ; their Quantitative De- 

 termination \A/-hen Occurring Together. 



BY DR. F. G. AVIECHMANN. 



Commercial Oil-testing. 



BY DR. H. T. VULTE. 



Petrographical Notes. 



BY JAMES F. KEMP. 

 I. 



A Remarkable Erratic from Aurora, Cayuga Co., N. Y. Nearly 

 a year ago, Professor J. W. Freley, of Wells College, Aurora, 

 called the writer's attention to a remarkable rock that had been 

 found by him as a boulder two feet or so in diameter, "in the bed 

 of a small ravine only a few rods south of Wells College." Its 

 angles are described as being quite well rounded. A moment's ex- 

 amination of a hand-specimen showed that it was something un- 

 usual, and more careful study of a larger supply which Professor 

 Freley kindly supplied, has corroborated the impression. The rock 

 belongs with the hitherto seldom described basic rocks, which lack 

 feldspar entirely, have a glassy base, and have been called monchi- 

 quite' when possessing much olivine, and fourchite' when lacking 



1 M. Hunter and H. Rosenbusch, Ueber Monchiquit, etc. Tsch. Min. ii. 

 Petrog. Mitth., xi, 1891, p. 445. 



2 .J. F. Williams, Igneous Rocks of Arkansas. Ann. Rep. State Geol., 1890, 

 vol. ii. 



